Ultra fine fly ash and a system for collecting the same

ABSTRACT

A system for collecting ultra fine fly ash from a dry fly ash removal system includes providing a bagfilter transport conduit for each bagfilter of the system. A vacuum shutoff valve is positioned in each bagfilter transport conduit The bagfilter transport conduit is selectively connected to an educator that is, in turn, selectively connected to a blower. The blower creates a vacuum flow in the transport conduit that draws the ultra fine fly ash from the bagfilter and deposits the ultra fine fly ash in a collection bin. This system allows a dry fly ash removal system to segregate fly ash by size and separately collect the ultra fine fly ash from the larger fly ash particles. The ultra fine fly ash has been found to be commercially valuable as a concrete admixture filler in various applications.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] This invention generally relates to the control of emissions fromcombustion processes such as coal-fired processes or other combustionprocesses that produce large quantities of solid fly ash particles. Moreparticularly, the present invention relates to a system and method forsegregating the separated fly ash particles based on particle size andcollecting the segregated particles into individual storage containers.Specifically, the present invention relates to a separation system thatallows ultra fine fly ash to be separately collected from a dry fly ashremoval system by providing a dedicated removal system for removing flyash particles only from the last separation device of the system.

[0003] 2. Background Information

[0004] The combustion of coal and other similar fuels produces molteninorganic matter that is carried away in the exhaust gas stream as thefuel burns. The molten inorganic matter cools as the exhaust streamflows away from the combustion and coalesces into spherical orellipsoidal ceramic particles in the general range of 0.01 to 500microns in diameter. These combustion by-product particles are known inthe art as fly ash.

[0005] Fly ash must be removed from combustion exhaust streams beforethe streams are exhausted to the atmosphere because of environmentalconcerns. Numerous methods and systems for removing fly ash are known inthe art that effectively remove the fly ash from an exhaust stream. Oneproblem common to all of these methods and systems is the cost ofdisposing of the collected fly ash. Although some of the fly ash may besold for various commercial purposes such as for fillers, most fly ashmust be landfilled at the expense of the company creating the fly ash.It is thus desired in the art to increase the quantity ofcommercially-valuable fly ash and consequently decrease the amount offly ash that must be landfilled.

[0006] One known system that separates fly ash from a combustion exhauststream is an electrostatic precipitator 12 depicted in FIGS. 1 and 2.Other systems 12 that will function with the concepts of the presentinvention are separation systems such as bag filters, cyclones, andothers know in the art. Separation system 12 may be positioned as thefinal cleaning step for an exhaust stream from a coal-fired powerproduction process. For instance, system 12 may be used in a powerproduction process where coal is burned to create heat that producessteam to run generators. The burning coal creates an exhaust streamcontaining fly ash that must be substantially removed from the streamaccording to federal regulations. System 8 is a Fly Ash Removal System(FARS) which transports ash from the hoppers of the separation device12. FARS 8 transports the fly ash pneumatically to a storage facility(i.e. silo, pond, etc). The conveying air can be either a pressure orvacuum system. In the example of system 8 depicted in FIG. 1, the ashenters system 8 directly from an inlet conduit 10 that receives ash fromelectrostatic precipitator 12 positioned above conduit 10 and receivesits transport air from air intake 11.

[0007] Inlet 10 feeds a primary supply line 14 that is in communicationwith a plurality of separation units 16. In this embodiment of system 8,four separation units 16 are connected to primary supply line 14 inparallel such that each unit 16 receives substantially equal amounts ofthe fly ash-laden transport air. In other embodiments, a separate,individual precipitator may be used to deliver fly ash-laden transportair to each unit 16 without departing from the concepts of the presentinvention. Additional or fewer units 16 may be provided based on flowrate, need, and desired redundancies. Further systems 8 for one or morepower producers may also utilize a silo 40 common to all systems 8.

[0008] Each separation unit 16 includes a feed line 18 that connectsprimary supply line 14 to a coarse separator 20 . In this example, eachcoarse separator 20 includes a primary separator 22 connected to asecondary separator 24. In the preferred embodiment of the presentinvention, each separator 22 and 24 is cyclone. Feed line 18 isconnected to the inlet of primary separator 22 such that the flyash-laden transport air is drawn into the separation chamber of primaryseparator 22. The transport air exits primary separator 22 through anoutlet 26 after at least a portion of the fly ash falls out of thetransport air stream into a primary receiver 28. The separated fly ashexists through a first gate 30 that selectively opens and closes theoutlet 32 to primary receiver 28. A storage hopper 34 is disposed belowoutlet 32 to collect the fly ash. The outlet 36 of storage hopper 34 isselectively opened and closed by a hopper gate 38. Storage hopper 34 ispositioned above a collection silo or storage container 40 that gathersfly ash from each separation unit 16. A pressure equalization system 35is provided to regulate the pressure in the system.

[0009] Outlet 26 of primary separator 22 is connected directly to theinlet 42 of secondary separator 24. Second cyclone 24 has an outlet 44through which the transport air is drawn and a secondary receiver 46where the fly ash removed by secondary separator 24 is temporarilycollected. The outlet 48 of secondary receiver 46 is selectively openedand closed by a secondary gate 50 that selectively opens secondaryreceiver 46 to storage hopper 34.

[0010] Outlet 44 is connected to the inlet 52 of a tertiary separator54. Each tertiary separator 54 is preferably a bagfilter in system 8.Other separators such as ceramic filters or other high efficiencyseparating devices known in the industry may also be used as thetertiary separator. Each bagfilter 54 is designed and configured toremove the smallest particles of fly ash from the transport air beforeit enters a vacuum pump 58. Bagfilters 54 thus function as a finalcleaning step for the transport air. A bagfilter transfer conduit 56connects outlet 44 of each coarse separator 20 to inlet 52 of bagfilter54. The transport air flow is pulled through system 8 by vacuum pump 58.

[0011] As is known in the art, bagfilter 54 may often use a collectionof fabric filters, similar to common household vacuum cleaners, but at amuch larger scale, to entrap air-borne particulate matter onto a filtersurface, allowing the largely particulate-free air to continue throughthe filter surface. During operation of bagfilter 54, particulate matterbuilds up on the surface of the filter. This buildup is commonly knownas the bag's cake. Cakes are frequently allowed to build up tothicknesses of approximately 0.25 inch or somewhat more betweenintervals of cleaning. Bags in operational bagfilters are cleaned ofcake buildup at periodic intervals that are determined by variables ofoperation and engineering design. The cleaning process often involvesblowing air backwards through the bag filters, shaking the bags, orbanging the tops of the bags, all of which cause a substantial portionof the filter cake to drop off the bags.

[0012] In system 8, the bags of each bagfilter 54 are cleaned byknocking the cakes off of the bags and dumping the cake material into anopen hopper 60. First gate 61 selectively opens and closes into atransfer hopper 62. Transfer hopper 62 is selectively opened and closedby a second gate 64 that controls access to silo 40. The fly ashseparated by bagfilter 54 is moved into hopper 62 and dumped into silo40. A pressure equalization system 63 is provided to control thepressure in the system because the bag filter is under vacuum and thesilo is not. As such, the fly ash collected in bagfilters 54 is mixedwith the fly ash collected in coarse separator 20 and is commonlydisposed. Silo 40 is emptied through a rotary conditioning drum 66 andinto a vehicle 68 that transports the fly ash to another location.

[0013] It has been discovered as part of the present invention that thefly ash collected in bagfilters 54 is commercially valuable and that itis desirable to separately collect this fly ash. It has been found thatthe fly ash collected in bagfilters 54 comprises a plurality ofparticles with 90% of the particles having a diameter of less than 10microns. It is known in the art that fly ash particles having diameterspredominantly smaller than 25 microns are known as fine fly ash. U.S.Pat. No. 4,294,750 discloses the benefits of fine fly ash particles. Thepresent invention refers to fly ash particles that are predominantlysmaller than 10 microns in diameter as ultra fine fly ash. It is thusdesired in the art to provide a system for collecting the fly ash frombagfilters 54 that does not combine the fly ash from bagfilters 54 withany fly ash from separators 22 and 24.

SUMMARY OF THE INVENTION

[0014] In view of the foregoing, it is an objective of the presentinvention to provide a method for separating ultra fine fly ash fromlarger fly ash particles in a dry fly ash removal system and collectingthe ultra fine fly ash particles for later use.

[0015] Another objective of the present invention is to provide a systemthat allows ultra fine fly ash particles to be collected separately fromlarger fly ash particles in a dry fly ash removal system.

[0016] Another objective of the present invention is to provide an ultrafine fly ash material having characteristics that are desired in fillersfor various applications.

[0017] Another objective of the present invention is to provide a systemand method for separating fly ash that results in less fly ash beinglandfilled.

[0018] Another objective of the present invention is to provide a systemand method for economically collecting ultra fine fly ash.

[0019] Another objective of the present invention is to provide asystem, as above, that may be retrofit into existing dry fly ash removalsystems.

[0020] Another objective of the present invention is to provide asystem, as above, that pneumatically transfers the separated ultra finefly ash to a dedicated storage container.

[0021] Another objective of the present invention is to provide asystem, as above, that selectively collects the ultra fine fly ash sothat the ultra fine fly ash only resides in the storage container ashort time prior to off-site transfer.

[0022] Another objective of the present invention is to provide aneffective, safe, inexpensive and efficient device that achieves all theenumerated objectives, provides for eliminating difficulties encounteredwith prior devices, and solves problems and obtains new results in theart.

[0023] These and other objectives and advantages of the presentinvention are achieved by a method for collecting ultra fine fly ashfrom a dry fly ash removal system having an inlet that directs a flyash-laden transport air stream into a coarse separator where a portionof the fly ash is removed from the transport air stream and a bagfilterin fluid communication with the outlet of the coarse separator where theultra fine fly ash is removed from the transport air stream; the methodincluding the steps of: (a) providing a transport conduit connected tothe bagfilter; (b) removing the ultra fine fly ash from the bagfilter;and (c) storing the ultra fine fly ash removed from the bagfilterseparate from the fly ash removed by the coarse separator.

[0024] Other objectives and advantages of the invention are achieved bya system for collecting particulate material, including an inlet; aseparator in fluid communication with the inlet; a bagfilter in fluidcommunication with the separator; a collection silo in selectivecommunication with the separator and the bagfilter; a gate configured toselectively block the fluid communication between the bagfilter and thecollection silo; and a transport conduit in fluid communication with thebagfilter between the gate and the bagfilter.

[0025] Further objectives and advantages of the present invention areachieved by particulate material, useful as a filler, composed ofparticles at least about 90 percent of which (volume basis) have aparticle size less than about 10 microns.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The preferred embodiments of the invention, illustrative of thebest mode in which applicant contemplated applying the principles of theinvention, are set forth in the following description and are shown inthe drawings and are particularly and distinctly pointed out and setforth in the appended claims.

[0027]FIG. 1 is a schematic view of a prior art dry fly ash removalsystem;

[0028]FIG. 2 is a schematic view of the portion of the dry fine fly ashremoval system encircled in FIG. 1;

[0029]FIG. 3 is a diagrammatic sectional view of the first and secondcyclones of the prior art dry fly ash removal system;

[0030]FIG. 4 is a diagrammatic sectional view of one bagfilter of theprior art dry fly ash removal system;

[0031]FIG. 5 is a schematic view of the ultra fine fly ash removalsystem of the present invention; and

[0032]FIG. 6 is schematic view of the encircled portion of the ultrafine fly ash removal system of FIG. 5.

[0033] Similar numbers refer to similar parts throughout the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0034] The ultra fine fly ash removal system of the present invention isindicated generally by the numeral 150 in FIGS. 5 and 6. System 150 maybe retrofit into system 8 and thus includes substantially all of theelements of system 8 and the numbers introduced above are used in FIGS.5 and 6 to indicate the elements of system 8. System 150 allows the flyash particles collected in bagfilters 54 to be separately collected fromthe fly ash particles collected in separators 20. Such segregatedseparation is desired because the ultra fine fly ash particles collectedin bagfilters 54 have been found to be commercially valuable. It hasbeen found that the fly ash particles collected in bagfilters 54 arepredominantly finer than 10 microns in diameter. In accordance with oneof the objectives of the present invention, the ultra fine fly ashparticles collected in bagfilters 54 are commercially useful asadditives and fillers for such applications as concrete, paint, sealant,polymers, etc. System 150 of the present invention allows these ultrafine fly ash particles to be easily collected from dry fly ash removalsystem 8 at selected times when such collection is desired.

[0035] System 150 is created by modifying system 8 by first providing asilo shutoff valve 169 and by providing an ultra fine fly ash transportconduit 152 that is in communication with a discharge chute 167positioned below each transfer hopper 62. The present invention alsocontemplates that transport conduit 152 may be connected directly tobagfilter 54 instead of the connection through hopper 62. Conduit 152may be connected to discharge chute 167 by an appropriate connector. Anair inlet check valve 158 allows air to flow into discharge chute 167from the surrounding atmosphere so that an ultra fine fly ash removalflow may be created in discharge chute 167 as will be described in moredetail below.

[0036] Each bagfilter transport conduit 152 is in selective fluidcommunication with an educator 160. The selective fluid communication isprovided by a vacuum shutoff valve 162 disposed between educator 160 anddischarge chute 167. Each educator 160 is in communication with airsupply line 165 that may be in selective fluid communication with an airsupply header 166. The selective communication between each air supplyline 165 and air supply header 166 may be provided by an air supplyshutoff valve 168 positioned between educator 160 and air supply header166.

[0037] Air supply header 166 is in fluid communication with a transportair blower 170 that is positioned at the upstream end of the air supplyheader 166. Transport air blower 170 includes an inlet filter 172 and anautomatic transport air dump valve 174.

[0038] Educator 160 is also in communication with an ultra fine ashtransport line 164. The downstream end of each ultra fine ash transportline 164 is in communication with an ultra fine fly ash storage silo176. Storage silo 176 is selectively connected to a transport vehicle178 by a suitable connection 180 such as a flexible chute. Storage silo176 also includes a compressed air flow inducer 182 and a dischargevalve 184. Storage silo 176 further includes an outlet filter 186.

[0039]FIG. 5 depicts each ultra fine ash storage silo 176 as a separatesilo for each separation unit 16. It is also contemplated by the presentinvention that a single silo 176 may be used with each ultra fine ashtransport line 164 extending from educator 160 to the single storagesilo 176. In this situation, air supply header 166 supplies pressurizedair to each air supply line 165 through a plurality of air supply shutoff valves 168.

[0040] In the preferred embodiment of the present invention, each airsupply line 165 and each ultra fine ash transport line 164 is fabricatedfrom two inch pipe with air supply header 166 being fabricated from fourinch pipe. Transport blower 170 may be a Holmes transport blower.Storage silo 176 may be sized to hold approximately 2,500 cubic feet ofultra fine fly ash with transport vehicle 178 being a dry bulk tanktruck. Valves 162, 168, and 184 may be manually operated orautomatically operated valves of any of a variety of suitable valvesknown in the art.

[0041] In normal operation of the dry fly ash removal system, vacuumshutoff valves 162 are closed and silo shutoff gates 169 are open withsystem 8 operating to remove fly ash from the transport air. The flyash-laden transport air stream is directed into separator 20 where thelarger particles of fly ash are removed and then directed intobagfilters 54 where the ultra fine fly ash is removed and discharged viatransfer hopper 62 to silo 40.

[0042] To collect the ultra fine fly ash, the user opens each transportair shutoff valve 168 to provide fluid communication between educator160 and blower 170. Blower 170 is then operated and let run for a fewminutes to warm the piping system and drive off any condensation. Theultra fine fly ash from each bagfilter 54 may then be collected byclosing silo shutoff gate 169, thus allowing ultra fine fly ash tocollect in the discharge chute 167, and opening its vacuum shutoff valve162 to create the ultra fine fly ash removal flow in the form of avacuum flow through its transport conduit 152. The removal flow drawsthe ultra fine fly ash from discharge chute 167 into transport air line164 where it is transported into storage silo 176. Transfer hopper 62feeds discharge chute 167 while the process continues.

[0043] In other embodiments of the present invention the ultra fine flyash may be removed from the bagfilter by positioning the bagfilterbetween its transport conduit 152 and a blower that creates the ultrafine fly ash removal flow through transport conduit 152. System 150 willalso function with gate 61 closed prior to evacuating hopper 62.

[0044] In some embodiments of the present invention, each bagfilter 54may be exposed to an ultra fine fly ash removal flow simultaneously. Inother embodiments, bagfilters 54 are sequentially exposed to the ultrafine fly ash removal flow such that ultra fine fly ash is only removedfrom one bagfilter at a time.

[0045] During the removal process, the operator monitors the height ofthe material in storage silo 176. In one example, the expectedcollection rate for a system 150 having four bagfilters 54 isapproximately 1,500 pounds per hour per bagfilter, or three tons perhour for collecting all four bagfilters 54. The expected collection timefor a 23 ton dry bulk truck is thus approximately seven to eight hours.

[0046] In one example taken from the baghouse at the Sporn plant locatedin New Haven, W.Va., which primarily burns low sulfur, easternbituminous coal, the ultra fine fly ash collected from the baghousecomprised particles of which 90% (volume basis) had a diameter of lessthan about 10 microns. About 50% (volume basis) of the ultra fine flyash particles had a diameter of less than about 3.7 microns. Theparticles had a specific gravity of 2.31, a moisture content of 0.18%, aloss on ignition of 5.44%. The autoclave expansion (per ASTM C-151) of acomposite cement paste made with 400 g of Portland cement and 100 gultra fine fly ash is within the specification and typically results ina negative valve (e.g. −0.05%). The pozzolonic activity of this sampleof ultra fine fly ash measured in accordance with ASTM C-311 (with thewater requirement being 100% of the control) is better than most class Fashes. Replacing 25% of the Portland cement in comparison with a 100%Portland cement control resulted in a compressive strength of 92% of thecontrol at 7 days which is well within the requirements of the ASTMC-618.

[0047] The analysis of the ultra fine fly ash resulted in 53% silica(SiO₂); 27.6% aluminum oxide (Al₂O₃); 7.9% iron oxide (Fe₂O₃); 1.4%titanium oxide (TiO₂); 1% calcium oxide (CaO); 0.7% magnesium oxide(MgO); 0.3% sodium oxide (Na₂O); 2.2% potassium oxide (K₂O); 0.6% sulfurtrioxide (SO₃); 0.3% phosphorous pentoxide (P₂O₅); 0.1% barium oxide(BaO); less than 0.1% manganese oxide (Mn₂O₃); less than 0.1% strontiumoxide (SrO); 4.5% total carbon, and 0.4% net ignition loss (+)/gain(−).The tests also revealed a loss on ignition (LOI) at 750° Celsius of 5.3;a pH at 25° Celsius, s.u. (1% slurry) of 4.9; and a specific conductanceat 25° Celsius, μmh (1% slurry) of 139.

[0048] In general, the ultra fine fly ash particles have a specificgravity in the range of 2.1 to 2.4 and a hegman fineness in the range of5 to 8. The pH falls in the range of 4.5 to 7 and the bulk density fallsin the general range of 40 to 60 pcf. The loss on ignition is also lessthan 8 percent.

[0049] Accordingly, the ultra fine dry fly ash collection system issimplified, provides an effective, safe, inexpensive, and efficientdevice which achieves all the enumerated objectives, provides foreliminating difficulties encountered with prior devices, and solvesproblems and obtains new results in the art.

[0050] In the foregoing description, certain terms have been used forbrevity, clearness, and understanding; but no unnecessary limitationsare to be implied therefrom beyond the requirement of the prior art,because such terms are used for descriptive purposes and are intended tobe broadly construed.

[0051] Moreover, the description and illustration of the invention is byway of example, and the scope of the invention is not limited to theexact details shown or described.

[0052] Having now described the features, discoveries, and principles ofthe invention, the manner in which the ultra fine dry fly ash collectionsystem is constructed and used, the characteristics of the construction,and the advantageous new and useful results obtained; the new and usefulstructures, devices, elements, arrangements, parts, and combinations areset forth in the appended claims.

1. A method for collecting ultra fine fly ash from a dry fly ash removalsystem having an inlet that directs a fly ash-laden transport air streaminto a coarse separator where a portion of the fly ash is removed fromthe transport air stream and a bagfilter in fluid communication with theoutlet of the coarse separator where the ultra fine fly ash is removedfrom the transport air stream; the method comprising the steps of: (a)providing a transport conduit connected to the bagfilter; (b) removingthe ultra fine fly ash from the bagfilter; and (c) storing the ultrafine fly ash removed from the bagfilter separate from the fly ashremoved by the coarse separator.
 2. The method of claim 1, wherein step(b) includes the step of exposing the bagfilter to a removal flow. 3.The method of claim 2, wherein the step of exposing the bagfilter to aremoval flow includes the step of educing a vacuum flow and exposing theultra fine fly ash in the bagfilter to the vacuum flow.
 4. The method ofclaim 3, wherein the step of educing a vacuum flow includes the steps ofproviding an educator in selective communication with the bagfilter anddirecting a transport flow through the educator to create a vacuum flowin communication with the bagfilter.
 5. The method of claim 4, furthercomprising the step of temporarily storing the ultra fine fly ash in astorage silo after it is removed from the bagfilter.
 6. The method ofclaim 5, further comprising the step of moving the ultra fine fly ashfrom the storage silo to a transport vehicle.
 7. The method of claim 4,further comprising the step of blocking the fluid communication betweenthe educator and the bagfilter after the ultra fine fly ash has beenremoved from the bagfilter.
 8. The method of claim 4, further comprisingthe step of providing a blower in fluid communication with the educatorand running the blower to remove condensation prior to the step ofeducing a vacuum flow in the bagfilter to draw the ultra fine fly ashout of the bagfilter.
 9. A method for collecting ultra fine fly ash froma dry fly ash removal system having at least one inlet that directs afly ash-laden transport air stream into at least two coarse separatorswhere a portion of the fly ash is removed from the transport air streamand selectively deposited in a collection silo and a bagfilter in fluidcommunication with the outlet of each coarse separator where ultra finefly ash is collected and selectively deposited in the collection silo;the method comprising the steps of: (a) blocking the communicationbetween a first bagfilter and the collection silo; (b) providing fluidcommunication between the first bagfilter and a transport air line; (c)removing the ultra fine fly ash from the first bagfilter; (d) blockingthe fluid communication between the first bagfilter and the transportair line; (e) blocking the fluid communication between a secondbagfilter and the collection silo after the ultra fine fly ash has beenremoved from the first bagfilter; (f) providing fluid communicationbetween the second bagfilter and a transport air line; (g) removing theultra fine fly ash from the second bagfilter; and (h) blocking the fluidcommunication between the second bagfilter and the transport air lineafter the ultra fine fly ash has been removed from the second bagfilter.10. The method of claim 9, further comprising the steps of: blocking thefluid communication between a third bagfilter and the collection siloafter the ultra fine fly ash has been removed from the second bagfilter;providing fluid communication between the third bagfilter and antransport air line; removing the ultra fine fly ash from the thirdbagfilter; and blocking the fluid communication between the thirdbagfilter and the transport air line after the ultra fine fly ash hasbeen removed from the third bagfilter.
 11. The method of claim 10,further comprising the steps of: blocking the fluid communicationbetween a fourth bagfilter and the collection silo after the ultra finefly ash has been removed from the third bagfilter; providing fluidcommunication between the fourth bagfilter and an transport air line;removing the ultra fine fly ash from the fourth bagfilter; and blockingthe fluid communication between the fourth bagfilter and the transportair line after the ultra fine fly ash has been removed from the fourthbagfilter.
 12. A system for collecting particulate material, comprising:an inlet; a separator in fluid communication with the inlet; a bagfilterin fluid communication with the separator; a collection silo inselective communication with the separator and the bagfilter; a gateconfigured to selectively block the fluid communication between thebagfilter and the collection silo; and a transport conduit in fluidcommunication with the bagfilter between the gate and the bagfilter. 13.The system of claim 12, further comprising an air inlet check valvedisposed between the gate and the bagfilter.
 14. The system of claim 12,further comprising an educator in selective fluid communication with thebagfilter.
 15. The system of claim 14, further comprising a vacuumshutoff valve selectively blocking the fluid communication between thebagfilter and the educator.
 16. The system of claim 14, furthercomprising a blower in selective fluid communication with the educator.17. The system of claim 16, further comprising an air supply shutoffvalve providing the selective fluid communication between the blower andthe educator.
 18. The system of claim 16, further comprising acollection bin and a transport air line in fluid communication with theeducator and the collection bin.
 19. The system of claim 18, furthercomprising an outlet filter connected to the collection bin.
 20. Thesystem of claim 19, further comprising a compressed air inducerconnected to the collection bin.
 21. The system of claim 20, furthercomprising a discharge valve connected to the collection bin.
 22. Thesystem of claim 12, further comprising a second separator in fluidcommunication with the inlet; a second bagfilter in fluid communicationwith the second separator; a second gate selectively blocking the fluidcommunication between the second bagfilter and the collection silo; anda second transport conduit in fluid communication with the secondbagfilter.
 23. The system of claim 22, further comprising a thirdseparator in fluid communication with the inlet; a third bagfilter influid communication with the third separator; a third gate selectivelyblocking the fluid communication between the third bagfilter and thecollection silo; and a third transport conduit in fluid communicationwith the third bagfilter.
 24. The system of claim 23, further comprisinga fourth separator in fluid communication with the inlet; a fourthbagfilter in fluid communication with the fourth separator; a fourthgate selectively blocking the fluid communication between the fourthbagfilter and the collection silo; and a fourth transport conduit influid communication with the fourth bagfilter.
 25. In a dry fly ashremoval system having an inlet; a separator in fluid communication withthe inlet; and a bagfilter in fluid communication with the separator,and a collection silo in selective communication with the separator andthe bagfilter; the improvement comprising: a bagfilter transport conduitconnected to the bagfilter such that fly ash may be removed from thebagfilter and collected and stored separately from the fly ash collectedin the separator.
 26. The improvement of claim 25, further comprising aneducator in selective fluid communication with the transport conduit.27. The improvement of claim 26, further comprising a vacuum shutoffvalve disposed between the educator and the bagfilter; the vacuumshutoff valve configured to provide the selective fluid communicationbetween the educator and the bagfilter discharge chute.
 28. Theimprovement of claim 26, further comprising: a storage silo; a transportair line extending between the educator and the storage silo; a blower;an air supply header in fluid communication with the blower; an airsupply line in fluid communication with the educator; and an air supplyshutoff valve providing selective fluid communication between the airsupply header and the air supply line.
 29. The improvement of claim 28,wherein the blower has an inlet and a filter in fluid communication withthe inlet.
 30. The improvement of claim 28, further comprising an outletfilter connected to the collection bin.
 31. The improvement of claim 30,further comprising a source of compressed air in fluid communicationwith the collection bin.
 32. The improvement of claim 31, furthercomprising a transport vehicle selectively connected to the collectionbin.
 33. The improvement of claim 32, further comprising a flexiblechute connecting the collection bin to the transport vehicle.
 34. Theimprovement of claim 25, further comprising an air inlet check valve influid communication with the bagfilter transport conduit.
 35. A methodfor collecting ultra fine fly ash comprising the steps of: directing afly ash-laden transport air stream into a separator; removing a portionof the fly ash from the transport air stream in the separator; directingthe transport air stream with the remaining fly ash into a bagfilter;removing the ultra fine fly ash from the bagfilter; and storing theultra fine fly ash separately from the fly ash removed by the separator.36. The method of claim 35, further comprising the steps of educing avacuum flow and exposing the bagfilter to the vacuum flow to remove theultra fine fly ash from the bagfilter.
 37. The method of claim 36,further comprising the step of providing a storage container inselective communication with the bagfilter and providing selectivecommunication between the storage container and the bagfilter. 38.Particulate material, useful as a filler, composed of particles at leastabout 90 percent of which (volume basis) have a particle size less thanabout 10 microns.
 39. The particulate material of claim 38, wherein theparticles have a well-defined, regular, ellipsoidal shape.
 40. Theparticulate material of claim 38, in combination with at least onepolymeric media.
 41. The particulate material of claim 38, wherein theparticles have a specific gravity in the range of 2.1 to 2.4.
 42. Theparticulate material of claim 41, wherein substantially 50% (volumebasis) of the particles have a diameter of less than about 3.7 microns.43. The particulate material of claim 38, wherein the particles are usedas a mineral admixture in Portland cement concrete.
 44. The particulatematerial of claim 38, wherein the particles are used as a mineralfiller.